Hidden away around the continent are shelters for survivors. They vary in type and size. Some serve as temporary stops. Others are more permanent. With the collapse of government, each is controlled by a different group. Some more civilized than others.
Shelters in the remaining cities are usually set up on the higher floors, with the ground level being sealed and all access to the above floors sealed. It's well known the infected are very poor climbers. The higher one can get, the safer they will be from attack.
Rural areas have opted more for walls and ditches filled with water, or islands in the middle or lakes and rivers. Shipping containers have found a new life. Stacked in a L formation, two wide on the bottom and two high on the outside, they become a formidable barrier against attack. Some have also dug the ground in front of the shipping container wall and filled the lower, outer containers with the dirt. The ditch is then filled with water or some other form of defense, such as long spikes.
Not all shelters are open to all people. Some are community based, and open only to people of their community. Others, may allow a person to visit for a time for a price, usually items of trade their group can use to better their own survival.